Polyester fiberfill has become widely used and well accepted as a relatively inexpensive filling material for pillows, quilts, sleeping bags, apparel, furniture cushions, mattresses and similar articles. It has generally been made of polyethylene terephthalate staple (i.e. cut) fibers that have been cut from filaments crimped in a stuffer box-type of crimper. The deniers (or dtex) of the fibers have generally been of the order of 5-6, i.e. a significantly higher denier per filament (dpf) than cotton fibers and polyester textile fibers used in apparel; this is because an important requirement for most filling material has been its resilience. The fibers may be hollow or solid, and may have a regular round or another cross section, and are cut to various lengths according to the requirements of the end-use or the process.
Polyester fiberfill is often "slickened", i.e. coated with silicones and more recently with polyethylene terephthalate/polyether segmented copolymers, to reduce the fiber/fiber friction. A low fiber/fiber friction improves the hand of the finished article made from the fiberfill, producing a slicker and softer hand, and contributes to reducing a tendency of the fiberfill to mat (or clump together) in the article during use.
Polyester fiberfill staple has generally been processed by being opened and then formed into webs which are cross-lapped to form a wadding (also referred to as a batt) which is used to fill the article. The performance of articles that have been filled using this technique has been satisfactory in many end-uses for many years, but could not fully reproduce the aesthetics of natural fillings such as down and down/feather blends. Such natural fillings have a structure that is fundamentally different from carded polyester fiberfill batts; they are composed of small particles with no continuity of the filling material; this allows the particles to move around within the ticking and to adapt the shape of the article to the user's contours or desires. We believe that the ease with which down and feather fillings can move around plays a key role in their recovery from compression after being compacted, by simple shaking and patting. This virtue is referred to as refluffability.
Contrary to down and feather, the carded polyester fiberfill batts have a layered structure, in which the fibers are parallelised, and are loosely interconnected within each web and between the layers so they cannot be moved around and refluffed in a similar way to down and feather. Polyester fillings have, however, some advantages over natural fillings, particularly in regard to washability and durability. Accordingly, Marcus has developed a fiberfill product composed of small, soft polyester fiber clusters or fiberballs which keep their identity during wear and laundering and enable the user to refluff the article filled with the fiberfill. These clusters combine the good mechanical properties and washability of polyester fiberfill with the refluffability of down or down/feather blends.
Although some particulate products had been produced commercially on modified cards from standard fiberfill, such products were prepared for different end-uses, and did not have the properties required for manufacture of high quality bedding or furniture articles. Steinruck disclosed one such modified card and process for making "nubs" in U.S. Pat. No. 2,923,980.
Marcus made his new fiberballs using fibers with specific characteristics as feed for a new fiberball-making process. U.S. Pat. Nos. 4,618,531 and 4,783,364 (referred to above) disclosed preferred fiberball products and a process to produce them from spiral crimp (including omega crimp) feed fibers, which can be rolled under mild conditions due to their potential for spontaneous curling. These products have been commercially successful in the U.S. and Europe, mainly in bedding and furniture cushions. Marcus demonstrated that such "spiral crimp", which some people prefer to refer to as "helical crimp", was important for achieving the desired fiberball structure, i.e. in providing a desired random arrangement of the fibers within each fiberball, and in achieving a desired low cohesion between the surfaces of neighboring balls. Commercial fibers with standard mechanical crimp did not produce fiberballs having the desired fiberball structure which provides good durability, high filling power and low cohesion, which are key requirements for refluffable filling products.
To optimize the filling power (i.e. to increase the bulk) and durability (i.e. to lower the amount of bulk lost during use), and particularly the durability to laundering, we believed that the entangled fibers forming the fiberball structure should be randomly distributed, should have a uniform density throughout the structure, and should be sufficiently entangled to keep the fiberball identity through laundering or during normal wear. To achieve optimum filling power and durability, we believed it to be important that each such fiber within the fiberball should have its bulk fully and individually developed, so that it could fully contribute (to the filling power and to the durability). To achieve this structure, on which depends the performance of the fiberballs, Marcus used fibers which tend to spontaneously curl, so that a good, consolidated structure could be produced under very mild forces. In the aforesaid patents, Marcus disclosed a preferred way to achieve this desired fiberball structure and properties by using fibers with helical crimp as feed fibers and an air tumbling process to roll the fibers under mild forces. The resulting products are characterized by a random distribution of the fibers within the fiberball, by being at least 50% round (having a ratio of the largest dimension to the smallest dimension of less than 2:1) and by having a low cohesion which was not shown in prior products. Marcus did not produce acceptable fiberballs under the same conditions using commercial fibers with standard mechanical crimp.
The feed fibers used by Marcus to make his new fiberballs were relatively unusual, unavailable and/or expensive in some markets, in which by far the majority of polyester staple fiber were crimped mechanically, generally by a stuffer box technique. After Marcus disclosed the value of using fiberfill in the form of a fiberball, rather than as parallelised fibers in a carded batt-type structure, it was desirable to find out why standard mechanically crimped fibers did not make good fiberballs, and to provide a feed fiber other than what Marcus used. Snyder et al in copending U.S. application Ser. No. 07/840,285 (referred to above) disclosed another process and apparatus for making fiber clusters, and succeeded in processing mechanically crimped feed fiber into satisfactory fiber clusters. An important object of parent applications 07/589,960, now U.S. Pat. Nos. 5,112,684, and 07/820,141 (referred to above) was to provide such mechanically crimped feed fiber that has the capability of being processed into such clusters, sometimes termed fiberballs. As expressed therein, the principles of the parent invention can also be applied to making clusters from fibers other than polyester fiberfill.
Removable, refluffable cushions are now typical in modern furniture styling. This has created a new need for refluffable fiberfill, so the cushions can be replumped. Furniture also requires filling products having more support and filling power than bedding or apparel. This sometimes requires fibers of higher denier, such as may require different crimping conditions from fibers of the order of 5-6 denier or dtex.
Accordingly, as disclosed in the parent applications, it was found that fiberballs with comparable properties could be produced from certain mechanically crimped fibers which have specific crimp configurations. An important characteristic is believed to be a potential to curl spontaneously that is similar in this respect to that of the spiral crimped fibers used as feed fibers by Marcus. Suitable feed fibers have been used with combinations of primary and secondary crimp with specific ranges of frequency and amplitudes. The precise ranges of values required will depend on various considerations, such as the denier and configuration of the feed fiber, and the process technique used to make the balls. The frequency and amplitude of the secondary crimp, especially, and good heat setting of this secondary crimp, are believed to be key requirements for making fiberballs.
Accordingly, one aspect of the parent invention was to provide refluffable fiberballs having a uniform density, and a random distribution and entanglement of fibers within each ball characterized in that the fiberballs have an average cross-section dimension of about 2 to about 20 mm, and that the individual fibers have a length in the range of about 10 to 100 mm and are prepared from fibers having a primary crimp and a secondary crimp, said primary crimp having an average frequency of about 14 to about 40 crimps per 10 cm and said secondary crimp having an average frequency of about 4 to about 16 crimps per 10 cm, and having an average amplitude from the fiber longitudinal axis of at least 4 times the average amplitude of the primary crimps.
Also provided were fiberballs having a random distribution and entanglement of fibers within each ball, said fibers being a blend of load bearing fibers and binder fibers, which optionally contain a material capable of being heated when subjected to microwaves or a high frequency energy source, characterized in that the fiberballs have an average diameter of from about 2 mm to about 20 mm and the individual fibers have a length of about 10 to about 100 mm, the load-bearing fibers having primary crimp and a secondary crimp, said primary crimp having an average frequency of about 14 to about 40 crimps/10 cm and the said secondary crimp having an average frequency of from about 4 to about 16 crimps/10 cm, and whereby the average amplitude of the secondary crimp is at least 4 times the average amplitude of the primary crimp.
Further provided were processes for making the aforesaid fiberballs as more fully described therein.
Additionally provided were molded structures prepared from fiberballs which contain binder fibers.
Other aspects of the invention were preferred feed fibers for making the fiberballs, and processes involved in making suitable feed fibers.
Accordingly, processes were provided for mechanically crimping a tow band of polyester filaments of lower denier (about 4 to about 10 dtex) per filament in a stuffer box crimper at a crimper loading of about 13 to about 26 ktex per inch of crimper width, and for heat-setting the crimped tow band to provide crimped filaments having a primary crimp with an average frequency of about 14 to about 40 per 10 cm and a secondary crimp with an average frequency of about 4 to about 16 per 10 cm, and an average amplitude at least 4.times. the average amplitude of the primary crimp and for converting the resulting crimped tow band into cut fiber to provide feed fiber for a process for making fiberballs from such feed fiber, and for making such fiberballs by an air-tumbling process or by using a ball-making machine equipped with card clothing, e.g. of the modified roller-top type, or as disclosed, e.g., by Snyder et al. in U.S. application Ser. No. 07/840,285, and preferred mechanically-crimped feed fiber for use in such ball-making machines and processes. Similar processes provided for polyester filaments of higher dtex, with crimper loadings, e.g., up to about 34 ktex per inch, correspondingly. The appropriate crimp need not be induced only by use of a mechanical crimper of the stuffer box-type, for example, but alternative methods of inducing the appropriate structure, were also contemplated.